In the field of portable cellular radiotelephones, notably GSM (Global Standard Mobile), for example, a memory circuit, such as an electronic card is known to be used which can be removably inserted into the telephone. Data notably relating to the identity of the user are read from the card which has been inserted and these data are then used during subsequent operation of the apparatus.
The electronic card may be, for example, a card called chip card or smart card of the ISO format which is the format of a common credit card and which has a memory arranged in the form of an integrated circuit. This circuit and its external contacts, or contact terminals, which are flush with the surface of the card in fact occupy only a very small part of this card as regards volume and surface.
In modern telecommunication systems, the applications linked with the use of chip cards are on the increase. One of these applications relates to the circuit called Subscriber Identity Module (SIM) proposed for the pan-European digital cellular radiotelephone system. On this subject reference be made to Recommendation GSM 11.11 of ETSI, which describes the specifications and the recommendations GSM 02.17 which relate to the functional characteristic features of the SIM.
Two different mechanical standards are proposed for the GSM SIM card. The functionalities are the same for the two sizes, but the physical dimensions differ, except for the thickness of the cards which is equal to 0.8 mm. These two standards are the ISO SIM, also called large card in the present text, having the dimensions of a credit card, and the Micro SIM, or small card, which measures 20 mm.times.25 mill. The ISO SIM is relatively large and the need for smaller cards is felt as the miniaturization continues to reduce the size of the radiotelephone handset itself. The reduction of the card to the Micro SIM format is favourable to this miniaturization effort.
In principle, a radiotelephone is designed for receiving either of the two SIM cards mentioned above which will have to coexist. For a smoother use it is desirable to design a radiotelephone which is suitable for receiving either SIM card. This may be found to be necessary when one wishes to lend one's radiotelephone to a person who has a SIM card of a different format from that of the owner of the apparatus. A solution to this technical problem is known, notably from European Patent No. 0 556 970 Al. The radiotelephone which is described there comprises an adapter which is placed in a cavity so as not to form an obstacle to the insertion of the card when the adapter is arranged in the reading mode of a chip card of the larger format and, when arranged in the reading mode of a Micro SIM card, or smaller format, tilts by means of a pivot link and presses the contact pads of the card against the corresponding terminals of the electronic card reader. The pivotal mounting used presents one drawback: while the adapter is tilted, it protrudes from the body of the apparatus and then becomes vulnerable to shock. Furthermore, this solution is not favourable to a reduced bulkiness in the reader of the radiotelephone, since the latter is suitable for containing the two cards at the same time, the large one in the reading position and the small one in the storage position while the two are overlying each other.
It is an object of the invention to provide a single and robust adapter means for a Micro SIM card in an ISO SIM card reader which adapter means does not increase the cumbersomeness for positioning a card of the ISO SIM format in the card reader.
A further object of the invention is that an adapter means for the Micro SIM card is always irremovably present in an electronic card reader.
A still further object of the invention is that a Micro SIM card is precisel put in the reading position in an electronic card reader in a simple and economic manner.